Pounds Per Square Foot 10 ft. radius 10 - 20 ft. radius 20 - 30 ft. radius Total 1.89 1.82 1.85 0.10 0.12 0.04 0.188 0.386 0.246 1.84 0.08 0.286 Samples of the vegetation were analyzed for radionuclide content at the University of Washington. These data were not available at the publication time of this report and will be included in a later report. While clearing of vegetation has no significant immediate effect, it is possible that certain long range effects could lead eventually to somewhat lower radiation levels. Since water is no longer taken up by the plants, the flow of ground water is disrupted. This factor and the subsequent weathering of the cleared area could cause less retention of fallout products near the surface of the ground. Thus, lower radiation levels in such an area might result. A careful soil depth profile (Table 2) was obtained from an area 25 feet west of the center of the cleared area. Also, several 6" diameter x 6" deep cores were taken along a radius to the north from the center at 10 foot intervals. The soil appeared to be of high organic content and had an average moisture content of about 10% and a bulk density of about 1.2 gm/cm®. The isotopes were found to be distributed with depth in a roughly exponential manner for the first 3 inches with an approximate relaxation length of 3 cm. However, the activity from 3 - 5" was much higher than allowed for by this exponential model. The exposure rates calculated for the total measured concentrations, assuming a 3 cm relaxation length is typical for the area as a whole, are given below along with the percentage of the total exposure rate due to each isotope. - 26 -